To determine whether patients with a HLA‐identical sibling donor have a better outcome than patients without a donor, an analysis on the basis of intention‐to‐treat principles was performed within the framework of the EORTC‐GIMEMA randomized phase III AML 8A trial. Patients in complete remission (CR) received one intensive consolidation course. Patients with a histocompatible sibling donor were then allocated allogeneic bone marrow transplantation (alloBMT), the patients without a donor were randomized between autologous BMT (ABMT) and a second intensive consolidation (IC2). 831 patients <46 years old and alive >8 weeks from diagnosis were included. HLA typing was performed in 672 patients. AlloBMT was performed during CR1 in 180 (61%) out of 295 patients with a donor. Another 38 patients were allografted: five in resistant disease, 14 during relapse and 19 in CR2. ABMT was performed in 130 (34%) out of 377 patients without a donor in CR1, in six (2%) patients during relapse and in 38 (10%) patients during CR2. The disease‐free survival (DFS) from CR for patients with a donor was significantly longer than for patients without a donor (46% v 33% at 6 years; P = 0.01, RR 0.78, 95% confidence interval 0.63–0.96). The overall survival from diagnosis for patients with a donor was longer, but not statistically significant, than for patients without a donor (48% v 40% at 6 years; logrank P = 0.24). When patients were stratified according to prognostic risk groups, the same trend in favour of patients with a donor was seen for survival duration and the DFS remained significantly longer for this group of patients.